package com.zyy;

public class demoString {
    public static void main(String[] args) {
        System.out.println("hello world");
        System.out.println(System.currentTimeMillis()); // 当前时间戳

//
        String s = "10";
        String  s1 = "hello world";
        int i = Integer.parseInt(s);
        System.out.println(s1.replace("world", "java"));
        System.out.println(s1.contains("world")+"");
        System.out.println(s1.toUpperCase());
//        System.out.println(s1.toUpperCase("df"));
    }
}
